390 ANATOMY OF VERTEBRATES. 



In the Hedgehog the squamosal is traversed by a vertical venous 

 canal. The malar is applied, like a splint, along the outer and 

 under side of the junction of the zygomatic with the maxillary. 

 The cranial cavity shows the rhinencephalic compartment to be 

 nearly equal in size vnth the epencephalic one : the petrosal is 

 impressed by a cerebellar fossa. The nasal passage terminates 

 behind in a hemispheric excavation of the basisphenoid ; and 

 this bone expands outwardly to form the floor of the tympanic 

 cavity. There are two oblong vacuities in the palatal bones. 



In the Gymnura the bony palate is entire. The premaxillaries 

 join the anterior half of the nasals. The lacrymal perforation is 

 in a small fossa at the fore-part of the orbit, which is not defined 

 from the temporal fossa. The zygomatic process of the squa- 

 mosal is long and slender, joining that of the maxillary. The 

 basisphenoid expands to form the floor of the tympanic cavity. 

 The superoccipital and parietal crests are well developed. The 

 pterygoid is pierced lengthwise by an ectocarotid canal. 



C. Bones of the Limbs. — All the Insectivora have perfect 

 clavicles. The scapula of the Hedgehog is almost as long as the 

 humerus ; the acromion is bilobed : the coracoid produced and 

 thick. The humerus is perforated between the condyles. The 

 antibrachials are distinct, but closely connected together : the 

 ulna being the larger and more compressed. The carpus consists 

 of a scapholunar bone, a cuneiforme and large pisiforme, a 

 trapezium, trapezoides, magnum and unciforme. A sesamoid is 

 attached to the outside of the base of the metacarpal of the 

 digitus minimus. The fibula coalesces at its distal end with the 

 tibia. The ectocuneiform and cuboides are elongated. The foot 

 is pentadactyle and plantigrade. 



In Aynphisorex the radius and ulna are closely united, and the 

 fibula appears as a slender process ascending from the middle of 

 the tibia. In the proboscidian Shrew {Rhynchocyoii) the pollex 

 is wanting, and the fifth digit has but two phalanges ; but the 

 index, medius, and annularis present the normal number of pha- 

 langes supported on long metacarpals. Besides the usual eight 

 carpals, there is an ' intermedium ' between the scaphoid, trape- 

 zium, trapezoides, and magnum. In the hind-foot there is a 

 rudiment of the metatarsal of the first toe, and the fifth has the 

 usual number of phalanges.^ 



The ]\Ioles exhibit the extremes of modification of the fore-limb 

 in relation to the power of making progress in earth. In Talpa 



